The background of the invention will be discussed in two parts.
1. Field of the Invention
This invention relates generally to the electrical connector devices, and more particularly to an electrical connector device and the method for manufacturing the same.
2. Description of the Prior Art
Electrical contact assemblies for electronic systems and devices have been utilized extensively. In many instances such contact assemblies are employed to facilitate initial fabrication and ultimately to facilitate service or replacement of subcomponents on a modular basis. One of the more commonly employed type of electrical contact assembly includes a plurality of contact elements, such as contact pins, in an array within an insulative body, for mating connection to a like number of arrayed aligned contact sockets configured for receiving the pins in sliding relation. Such electrical contact assemblies include some means for providing friction for insertion and retention of the pin within the socket. Such friction is typically accomplished by configuration of the socket with longitudinally extending slots or kerfs. In other such devices, the socket may be provided with a circumferentially reduced diameter portion.
In any event, with miniaturization and micro-miniaturization of electronic components and subassemblies, demands have been placed on manufacturers of electrical contact assemblies for smaller and smaller devices. Wiring techniques have progressed to "ribbon" conductors in which a generally flat ribbon or sheath incorporates an aligned row of a plurality of stranded or braided, very small gauge, conductors, equally spaced across the width of the ribbon. To facilitate coupling, connectors have been developed for "matching up" to the conductor spacing.
Electrical contact assemblies have been reduced in size to the point where contact pins may have a dimension in the order of 0.0125 inches for insertion in a socket having an outer diameter of 0.018 inches with adjacent sockets spaced on 0.025 inch centers providing a density of about 1000 contacts per square inch. Such reductions in size are accompanied by corresponding problems. One basic problem relates to the very small dimensions of both the contact pin and the socket, whereby the slightest transverse force can result in bending, or even breakage. In addition the contact assemblies must be capable of repeated insertions and withdrawals without significant distortion of the interconnecting parts which could result in lack of electrical integrity.
In providing electrical interconnection between fine gauge ribbon conductors and the connectors, soldering has been replaced by mechanical means, such as crimping. For crimping purposes, a portion of the insulator surrounding the conductor is removed exposing a length of each conductor in the ribbon. The conductors are positioned within tubular portions of the contact pin or socket and mechanical force is applied to deform the tubular portion to provide a mechanical coupling of the conductor therein. Such crimping may take any convenient form, but typically results in the crimped cross-section being in the shape of a star or figure eight, that is, the crimping force is applied from diametrically opposite sides of the tubular portion along a line. The crimping must be accomplished in such a manner that the strands of the conductor are not broken and must enable the conductor to be retained therein despite a pull in the axial direction of a minimum predetermined force.
In such connector assemblies, electrical contact in the separable sliding or telescoping members requires a minimum normal force between the members to establish a low electrical resistance gas tight junction. The normal force required varies with the metallic materials involved as well as the surface finish, roughness, plating and oxide films.
The most common contact system employed in electrical connector assemblies consists of a male contact or pin that telescopes into a female "spring" contact. The shape of the pin and socket may be round, square, triangular or rectangular in cross-section. Most spring sockets are designed of simple end supported beams formed by strips or longitudinal all of which are fabricated to provide one or more longitudinal arms that flex or deflect transversely, to provide the normal force to effect the electrical contact, when mated with the male member.
As a consequence of this geometry, the spring socket contact is lengthened. Furthermore, to test electrical circuits it is necessary to insert a probe into the spring socket and care must be exercised to ensure that the spring elements are not deflected beyond their elastic limits. To avoid such danger the common practice is to house the spring socket in a close fitting support sleeve or shroud as an integral part of the socket, or ensure that the cavity surrounding the contact provides the support to prevent this probe damage. Partially for this reason it is customary to house the socket within the insulator, and employ exposed cantilever contact pins for the mating connector. As a result of this geometry the more fragile member of the contact system is exposed and more easily damaged or bent.
An example of a connector assembly is shown and described in U.S. Pat. No. 3,047,832, issued to Deakin on Jul. 31, 1962, for "Electrical Socket Contacts", in which the socket is formed from bent sheet metal to define a longitudinal path for receipt of a contact pin, with the socket configuration providing spring action frictional resistance therebetween.
Another electrical connector assembly is shown and described in U.S. Pat. No. 3,277,422, issued to Shevlin on Oct. 4, 1966, for an "Electrical Connector Having Shrouded Pin Contacts". In this assembly the contact pins are encased in insulative material with a sleeve or shroud about the pin array. Similarly, the tubular socket members are encased in insulative material with a sleeve or shroud about the socket array.
Another electrical connector assembly is shown and described in U.S. Pat. No. 3,281,760, issued Oct. 25, 1966, to Shintaro Oshima et al, for "Electrical Connection Elements and Connectors", in which the geometric cross-sectional configurations of the plugs or pins are dissimilar from that of the jacks or sockets, thus creating longitudinal electrical contact and friction during insertion and retention due to the attempt of the plug to deform the jack.
A contact plug or pin is shown and described in U.S. Pat. No. 3,786,558, issued to McCarthy on Jan. 22, 1974, for a "Method of Making a Hollow Electrical Contact", in which the hollow contact is provided with spring action by longitudinal slotting.
U.S. Pat. No. 4,343,384, issued Aug. 10, 1982, to Mutter, for "Connector Apparatus for Electrically Conductive Guide Rails", and discloses axially slotted members and the fabrication thereof.
Another "Terminal Plug Body and Connector" is shown in U.S. Pat. No. 4,660,922, which issued to Cooney et al on Apr. 28, 1987.
U.S. Pat. No. 4,687,278, entitled "Contact Socket with Improved Contact Force" issued to Grabbe et al on Aug. 18, 1987 and discloses a square pin for insertion into a socket having four longitudinally extending beam portions flexed into the socket opening for contact with the square pin. Another spring contact jack is shown and described in U.S. Pat. No. 4,752,253, entitled " Contact Element and Method of Manufacturing", which patent issued Jun. 21, 1988, to Neumann et al, the contact having a plurality of mutually laterally disposed spring contacts arranged and dimensioned for contact with the sides of a plug inserted therein.
A similarly configured spring socket contact is shown and described in U.S. Pat. No. 4,753,616, entitled "Contact Element for an Electrical Plug Connector", which issued to Molitor on Jun. 29, 1988.
In accordance with an aspect of the invention, it is an object of the present invention to provide a new and improved electrical connector assembly and method for the manufacture thereof.